Primer for internal combustion engines



June 6, 1967 J. D. SANTI PRIMER FOR INTERNAL COMBUSTION ENGINES FiledFeb. 25, 1965 3 Sheets-Sheet l jmOnwfiLd J0 hn Eat-Liz J. D. SANTIPRIMER FOR INTERNAL COMBUSTION ENGINES Filed Feb. 23, 1965 June 6, 19673 Sheets-Sheet 2 A i .I

June 6, 1967 J. D. SANTI 3,323,293

PRIMER FOR INTERNAL COMBUSTION ENGINES 5 Sheets-Sheet 5.

Filed Feb. 23, 1965 III,

Ill/I United States Patent '0 Delaware Filed Feb. 23, 1965, Ser. No.439,502 9 Claims. (Cl. 55-385) This is a continuation-in-part of myapplication Ser. No. 378,576, filed June 29, 1964, now abandoned.

This invention relates broadly to internal combustion engines and refersmore particularly to the fuel supply systems of single-cylinder enginesof the type now widely used on lawn mowers, snow blowers, gardencultivators, and other similar implements.

The purpose and object of this invention is tomake starting of suchengines easier.

Conventionally, the carburetor in the fuel supply systems of smallsingle-cylinder gasoline engines was equipped with a choke valve tocontrol the admission of air and thereby regulate the richness of thefuel-air mixture drawn into the engine.

In starting the engine, the operator was expected to close the chokevalve so that the fuel mixture drawn into the engine during crankingwould be sufliciently rich to assure starting, and then as soon as theengine started the choke valve had to be reopened to prevent floodingthe carburetor. The need for making these adjustments was a source ofannoyance; and while the remote controls with which some engine-drivenimplements were equipped did facilitate actuation of the choke valve, anadjustment after the engine started still had to be made; and if it wasnot made promptly the engine would stall. This meant trouble, at leastto the inexperienced operator.

The present invention obviates the need for making such quickadjustments, by the simple expedient of replacing the choke valve of thecarburetor with a priming pump. It is realized that the use of primingpumps to inject fuel directly into the carburetor of an engine is notnew, but the manner in which the present invention combines the primingpump and the control thereof with the carburetor and the fuel tank ofthe engine to afford an extremely simple and inexpensive arrangement isbelieved to be novel.

The invention is particularly adapted to engines wherein the fuel tankand the carburetor are combined into a unitary assembly, with thecarburetor mounted on the top wall of the fuel tank, so. that fuel maybe drawn directly from the tank into the mixing passage of thecarburetor. In such carburetor-fuel tank assemblies, the air inletopening of the carburetor faces upwardly and has an air filter removablymounted thereon, the filter being held in place by a screw which passesaxially down through the air filter and is threaded into the bottom wallof the carburetor mixing passage.

With a view toward achieving utmost simplicity and economy inmanufacturing costs, this invention has as a specific object to providea carburetor-fuel tank assembly with a priming pump, which assembly isso arranged and constructed that the screw that holds the air filter inplace is tubular, and the actuator for the pump is slideably received insaid screw.

Another important objective attained in one embodiment of the presentinvention is to provide a primer pump for injecting a charge of fuelfrom a fuel tank into the air passage of a carburetor, which pump has avery simple cup-shaped plunger element and needs no valves.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiments of thehereindisclosed invention may be made as come within the scope of theclaims.

The accompanying drawings illustrate two complete examples of physicalembodiments of the invention, constructed according to the best modes sofar devised for the practical application of the principles thereof, andin which FIGURE 1 is a perspective view of a carburetor-fuel tankassembly embodying this invention, with parts broken away and insection;

FIGURE 2 is a view similar to FIGURE 1 but illustrating a modifiedembodiment of the invention;

FIGURE 3 is a vertical sectional view through the assembly shown inFIGURE 2, drawn to a larger scale and showing the plunger element of theprimer pump in its normal or discharging position;

FIGURE 4 is a View similar to FIGURE 3 but showing the plunger elementin its filling position; and

FIGURE 5 is a fragmentary sectional view taken on the same plane asFIGURES 3 and 4 and showing details of the passage which communicatesthe primer with the carburetor mixing passage.

Referring now particularly to the accompanying drawings, the numeral 5designates generally the entire carburetor-fuel tank assembly of thisinvention, and which comprises a fuel tank 6 having a top wall 7 and acarburetor 8 mounted on the top wall of the tank. The top wall 7 of thefuel tank and the carburetor body are preferably formed as die castings.

The carburetor has a mixing passage 9 with an upwardly facing air inlet10 at one end thereof and an outlet 11 at its other end that isconnected by a tube 12 to the intake port of the engine, not shown. Amounting flange 13 on the body of the carburetor seats fiat upon amounting pad on the top wall 7 of the fuel tank, and is remova-blysecured thereto by screws 14. A thin, re.- silient membrane-like gasket35, of neoprene or the like, is confined between the flange and themounting pad to provide a seal where fuel passages continue across thejunction between the fuel tank and the carburetor body.

Depending from the top wall 7 of the fuel tank is a fuel reservoir 15into which fuel is pumped from the tank by means of anengine-suction-responsive pump (not shown) and from which fuel is drawninto the mixing passage 9 through an eduction tube 16 which leads to aneedle valve controlled orifice that opens into the mixing passage.Since the manner in which fuel is pumped from the tank into thereservoir 15 and withdrawn from it into the mixing passage forms no partof the present invention, these features have not been detailed in thedrawing. Moreover, reference may be had to the copending Cattersonapplication, Ser. No. 270,949, now abandoned, which illustrates theseparticular features.

As in the past, an air filter 17 is removably held in position on theinlet end of the carburetor mixing passage by means of a long retainingscrew 18, which passes axially down through the air filter and isthreaded, as at 19, into the bottom wall of the mixing passage. Aknurled head 18' on the screw provides means by which the screw can beturned and a shoulder to bear down on the cover of the air filter.

The recently issued Lechten berg Patent No. 3,118,433, illustrates thegeneral organization thus far described; but whereas, in the priorstructures, the air inlet opening 10 was equipped with a choke valve tobe closed during cranking of the engine-at least when the engine wascoldthere is no such choke valve in the present invention. The air inletopening 10 leading to the mixing passage is always fully open.

To obtain the necessary enrichment of the fuel mixture l or startingpurposes, a priming pump, indicated generlly by the numeral 20, isprovided. This pump supplants he conventionally used choke valve, andupon actuation hereof, squirts a jet of fuel directly into the mixingpasage.

Simplicity and a remarkably practical construction .haracterize themanner in which the priming pump s incorporated into the carburetor-fueltank assembly. Thus as illustrated in FIGURE 1 the priming pump has ttubular element 21 which is cast integrally with the op wall 7 of thefuel tank, and more particularly, with he bottom of the reservoir 15,from which the tubular :lement rises inside the reservoir and projectsdownwardvy beneath the reservoir. The tubular element 21 has anulti-diameter bore that decreases stepwise in width toward the bottomthereof to provide a pair of vertically spaced upwardly facingcircumferential shoulders and 36 and to provide a plunger chamber orcylinder 21 of the pump in the widest portion of the bore, above theupper circumferential shoulder 25. The height of the plunger chamber 21is such that its open upper end bears against the underside of thecarburetor in line with a priming hole or port 22, which opens to themixing pas sage. Accordingly, upon upward movement of a plunger elementor piston 23 in the chamber 21, fuel contained in the plunger chamber isprojected through the hole or port 22 directly into the mixing passage.

The plunger element or piston 23 is biased upwardly by a compressionspring 24 confined between the plunger and the shoulder 25 at thejunction of the plunger chamber with a smaller diameter portion 26 ofthe bore of the tubular element, in its bottom portion. The tubularelement projects downwardly to a point near the bottom of the fuel tank,where it has an inlet port 27 defined by the smallest diameter portionof the bore therein. Fuel flow through the inlet port 27 is controlledby a ball check valve 27' that is gravity biased into engagement withthe lower circumferential shoulder 36, which serves as a seat for theball.

The plunger element or piston 23 is somewhat smaller in diameter thanthe bore of the plunger chamber 21, but has an integral, relativelyflexible upwardly facing circumferential lip 28 at its top which snuglyengages the bore of the plunger chamber when in its normal unflexedcondition. Hence, during upward movement of the plunger or piston, theball check valve is lifted off its seat and fuel is drawn from the tankinto the bottom portion of the tubular element 21; and upon depressionof the plunger or piston, the fuel trapped in the lower portion of thetubular element by closure of the ball check valve, deflects the lip 28,which thus may be considered a unidirectional valve means, and passes tothe top side of the plunger element or piston, to be lifted thereby andexpelled from the chamber through the outlet port 22 when the spring 24forces the plunger element or piston upward.

It is important to observe that the plunger chamber is coaxial with theupwardly opening inlet 10 of the mixing passage, and that the screw 18by which the air filter is held in place is tubular. By virtue of thiscoaxiality and the tubular nature of the screw 18, utmost simplicity inthe actuation of the pump is possible. Thus, as shown, an actuator stemor push rod 30 with a head or button 31 on its outer end, passesslidably down through the tubular retaining screw 18 to project into anelongated socket 32 in the plunger element 23. There is no need for thestem 30 to be fixed to the plunger, since the upward bias of the springon the plunger element holds it against the end of the stem and ashoulder 33 formed on the stem-'by pinching the same to form oppositelyprojecting earsengages the lower end of the tubular screw 18 to hold thesame against upward displacement beyond its normal potentially operativeposition.

In operating the priming pump, it is only necessary to momentarilydepress the actuating button 31. This forces down the plunger element orpiston 23 and causes fuel which had been trapped in the lower endportion of the plunger chamber by a preceding actuation of the piston,to pass between the flexible lip 28 of the piston and the wall of thechamber bore. Upon release of the button 31, the spring 24 forces thepiston up and, in so doing, expels the fuel from the plunger chamber andsprays or squirts it into the mixing passage 9 through the priming portor hole 22.

In the embodiment of the invention illustrated in FIG- URES 25, the aircleaner 17 is again secured in place on the upwardly opening inlet 10 ofthe carburetor mixing passage 9 by means of a tubular screw 18 which isthreaded, as at 19, into the bottom wall of the mixing passage; and anelongated stem or push rod 30' extends through the tubular screw, to beaccessible at the top thereof for actuation of a plunger element 23'. Inthis instance, too, the plunger element cooperates with a stationarytubular element 121 which is secured to and projects downwardly from thetop wall 7 of the fuel tank, in axial alignment with the tubular screw,and which has its lower end spaced above the bottom wall 47 of the fueltank.

However there is no check valve in the FIGURES 2-5 version of theinvention, and the plunger element 23 is cup-shaped and is disposedbeneath the tubular element to be moved to and from telescoping relationtherewith, so that the plunger element comprises a movable cylinder andthe tubular element comprises a cooperating stationary piston.

As shown, the tubular element 121 is made of material which issufficiently resilient to be deformable under substantial pressure andhas a larger diameter upper end portion 48 which is press fitted into ahole in the top wall 7 of the fuel tank, directly beneath and coaxialwith the threaded connection 19 of the tubular screw 18 to thecarburetor body. At least the lower portion of the tubular element has auniform outside diameter along its length so as to have a close slidingfit in the cupshaped plunger element 23'. To insure a good seal betweenthe sliding surfaces of the tubular element and the plunger element, thelatter preferably has a small radially inwardly projectingcircumferential flange or lip 49 around its rim portion.

The plunger element also has a radially outwardly projectingcircumferential flange 50 on its rim portion that provides a downwardlyfacing seat for a coiled compression spring 24 that surrounds thecylindrical wall of the plunger element and has its lowermostconvolution received in a well 51 in the bottom wall 47 of the fueltank.

The axial height of the cup-shaped plunger element is substantially lessthan the distance between the lower end of the tubular element 121 andthe bottom wall of the fuel tank therebeneath, so that when the plungerelement is fully depressed aganist the bias of spring 24', as shown inFIGURE 4, fuel from the tank can flow over its rim and fill the plungerelement.

Such downward displacement of the plunger element can be effected bymeans of the stem or push rod 30, which in this case is made in twosections and 230 so as to permit the air cleaner to be removed from thecarburetor body without the need for disassembly of the priming pump.The lower section 130 of the push rod is coaxially secured at its bottomto the bottom wall of the cup shaped plunger element, and may bethreaded thereinto, as shown, or formed integrally therewith. The lowerpush rod section 130 extends with a small clearance through the bore 51in the lower portion of the tubular element and projects upwardly ashort distance into a counterbore 52 in the upper end portion of thetubular element, where it endwise abuts the upper section 230 of thepush rod. The upper section 230, which extends through and projectsabove the tubular screw 18', can

have the same diameter as the lower section and has outwardly projectingcars 33 near its lower end which prevent its inadvertent withdrawal fromthe tubular screw.

In this instance the head 118 on the tubular screw is shown as generallycup-shaped, and its side wall has a large enough inside diameter toreceive the pushbutton 31 on the upper end of the push rod, and hassufficient depth so that it projects up nearly to the normal level ofthe pushbutton. The cup-shaped head 118 thus serves as a guard whichprevents inadvertent depression of the pushbutton.

It will be observed that the upper and lower push rod sections 230 and130 are normally maintained in endwise abutting relationship by gravityacting on the upper section 230, and that the plunger element isnormally fully telescoped over the lower end of the tubular elementunder the biasing force of spring 24, as illustrated in FIGURE 3.

To effect priming of an engine with the apparatus of FIGURES 2-5, thepushbutton 31 is fully depressed, to move the plunger element down toits filling position illustrated in FIGURE 4. Fuel very quickly fillsthe cupshaped plunger element and at the same time rises in the bore ofthe tubular element to substantially the level that obtains in the tank.When the pushbutton is released, spring 24' propels the plunger elementupwardly into telescoping relationship with the tubular element, to thenormal position shown in FIGURE 3. Because of the close sliding fitbetween the plunger and tubular elements, the tubular element displacesfuel out of the plunger element as the latter rises, and such displacedfuel is constrained to move upwardly along the bore of the tubularelement and through a small transfer passage 22 that communicates theupper end of the counterbore with the mixing passage in the carburetor.

As illustrated in FIGURE 5, the transfer passage 22' is valved toprevent air from being sucked into the bore of the tubular element whenthe plunger element is depressed, such valving being provided by aportion of the membrane-like gasket 35 that is confined between thecarburetor body and the top wall of the fuel tank. Specifically, the topwall of the fuel tank is formed with a small depression 55 in its uppersurface which is overlain by the gasket 35 and which is located directlybeneath an upwardly opening passage section 56 in the carburetor bodythat leads to the mixing passage. The depression 55 is also directlybeneath the inner end of a laterally extending groove 57 in theunderside of the carburetor body that defines a passage section leadingfro-m the upper end of the counterbore 52. The transfer passage 22'consists of passage sections 56 and 57 and a connecting section definedby depression 55. Under fluid pressure produced by the priming pump thegasket portion above the depression 55 is displaced down into thedepression to allow fuel to flow from passage section 57 to passagesection 56; :but when suction is manifested in passage section 57 themembrane is drawn up thereby to seal the inner end of that passagesection against the entry of air. In this manner assurance is had thatunder ordinary circumstances adequate priming can be effected by asingle depression of the pushbutton.

It will be observed that the lower end of the tubular element isbeveled, and the rim of the cup-shaped plunger element iscorrespondingly beveled at its inner surface, so that the plungerelement is guided into telescoping engagement with the tubular elementin spite of any lateral displacement of the plunger element that mightresult from the loose fit of the lower push rod section 130 in the boreof the tubular element.

From the foregoing description taken in connection with the accompanyingdrawings it will be apparent to those skilled in this art that thisinvention simplifies the starting of internal combustion engines bysupplanting the heretofore customary choke valve and its indecisiveaction and annoying need for adjustment both before and after cranking,substituting for the choke valve a conveniently and easily actuatedpriming pump; and that this invention achieves its purpose in a verypractical and exceedingly simple manner.

What is claimed as my invention is:

1. In combination:

(A) a fuel tank for an internal combustion engine,

said tank having a top wall;

(B) a carburetor mounted on the top wall of the fuel tank and having amixing passage with an upwardly facing air inlet;

- (C) an air filter seated on the inlet of the mixing passage;

(D) a tubular screw passing down through the air filter and threadedinto the bottom wall of the mixing passage to hold the air filter inposition;

(E) a priming pump carried by the top wall of the fuel tank and locatedinside the tank in line with said tubular screw, said priming pumphaving an inlet opening to the interior of the fuel tank and an outletwhich passes through the bottom wall of the mixing passage;

(F) a plunger for the priming pump; and

(G) an actuator for the plunger reciprocably received in the tubularscrew and having a handle portion at the upper end thereof.

2. An internal combustion engine fuel system of the type comprising afuel tank having a top wall, a carburetor mounted on said top wall andhaving a horizontally extending mixing passage with an upwardly facingair inlet, and an air filter removably seated on the inlet of the-mixingpassage, said fuel system being characterized by the following:

(A) a tubular screw passing down through the air filter and threadedinto the bottom wall of the mixing passage to hold the air filter inposition;

(B) a reciprocatory primer pump in the fuel tank, beneath said tubularscrew and coaxial therewith, said pump comprising (1) a stationaryupright tubular element having a bore that communicates at its upper endwith a passage that opens to the mixing passage and is communicable atits bottom with the interior of the fuel tank, and

(2) a plunger element which is movable up and down and which cooperateswith said tubular element for pumping fuel from the fuel tank to themixing passage; and

(C) an elongated actuator for said plunger element extending coaxiallythrough the tubular screw and having (1) a handle portion at its upperend, above the tubular screw, by which the actuator can be reciprocated,and

(2) a driving connection with the plunger at its lower end.

3. The internal combustion engine fuel system of claim 2 wherein saidprimer pump is further characterized :by the following:

(A) said upright tubular element is secured to the top wall of the fueltank and projects downwardly therefrom, and has its lower end spacedabove the bottom of the tank;

(B) said tubular element has a multi-diameter bore, decreasing in widthtoward the bottom thereof, to define (1) a lowermost upwardly facingcircumferential shoulder which provides a valve seat and (2) a higherupwardly facing circumferential shoulder which provides a spring seat;

(C) a gravity biased valve element cooperates with said valve seat topermit upward fiow of fuel through the bore in the tubular element andto block downward flow of fuel therethrough;

(D) the plunger element is reciprocable in the bore in the tubularelement above said spring seat and has a resiliently flexible radiallyprojecting lip that is normally in sealing circumferential engagementwith the inner Wall surface of the tubular element but is adapted to beflexed upwardly by the reaction of fuel to downward movement of theplunger element; and

(E) a coiled compression spring in said bore reacts between said springseat and the plunger element to bias the latter upwardly.

4. The internal combustion engine fuel system of claim 1 wherein saidprimer pump is further characterized by he following:

(A) said upright tubular element is secured to the top wall of the fueltank and projects downwardly therefrom, and has its lower end spacedabove the bottom of the fuel tank;

(B) the plunger element (1) is cup shaped,

(2) has a close telescoping fit with the lower end portion of thetubular element, and

(3) has an axial height which is substantially less than the spacebetween the lower end of the tubular element and the bottom of the tankso that the plunger element can occupy a position spaced below thebottom of the tubular element and in which fuel from the tank can flowinto the plunger element over its rim; and

(C) a coiled compression spring reacts between the bottom of the tankand the plunger element to bias the latter upwardly toward telescopedrelationship with the tubular element.

5. The internal combustion engine fuel system of claim 2, furthercharacterized by the fact that said tubular screw has a cup-shaped head,the bottom wall of which overlies the air filter to hold the same inplace and the side walls of which project upwardly and substantiallysurround the handle portion of the actuator to prevent inadvertentmovement of the same.

6. In an internal combustion engine fuel system having a fuel tank withopposite spaced apart top and bottom walls and a carburetor having amixing passage, a primer pump by which a charge of fuel can be injectedinto the mixing passage, said primer pump comprising:

(A) a stationary tubular element secured to the top wall of the fueltank and projecting downwardly therefrom with its lower end spaced adistance above the bottom wall of the fuel tank;

(B) means defining a passage which communicates the upper end portion ofthe bore in the tubular element with the mixing passage;

(C) a substantially cup-shaped plunger element having an inside diameterat its rim which provides a substantially close sliding fit with thelower portion of the tubular element and having a height less than thedistance between the bottom wall of the fuel tank and the bottom of thetubular element so that the plunger element is axially movable between alowermost filling position in which fuel from the tank can flow into theplunger element over the rim thereof and a discharging position in whichthe plunger element is telescoped over the lower portion of the tubularelement; I

(D) a compression spring reacting between the bottom wallof the fueltank and the plunger element to bias the latter towards its dischargingposition; and

(B) an upright push rod coaxially connected at its lower end with theplunger element, extending upwardly through the bore in the tubularelement, and having its upper end portion projecting above the t3tubular element to be accessible for depression of the plunger elementto its filling position against the bias of said spring.

7. An internal combustion engine fuel system of the type comprising afuel tank having a top wall, a carburetor mounted on said top wall andhaving a horizontally extending mixing passage with an upwardly facingair inlet, and an air filter, said fuel system being characterized by:

(A) means for readily detachably holding the air filter seated on theinlet of the mixing passage, comprising (1) a tubular element extendingthrough the air filter and having a connection with the bottom wall ofthe mixing passage, and

(2) means having a connection with the upper end of the tubular elementand having a downwardly facing shoulder which overlies the air filter,one of said connections being readily detachable;

(B) a reciprocatory primer pump in the fuel tank, beneath said tubularelement and coaxial therewith, said pump comprising (1) a stationaryupright tubular pump member having a bore that is communicated at itsupper end with the mixing passage and is communicable at its bottom withthe interior of the fuel tank, and

(2) a plunger member which is movable up and down and which cooperateswith said tubular pump member for pumping fuel from the fuel tank to themixing passage; and

(C) an elongated actuator for said plunger member extending coaxiallythrough the tubular element and having (1) a handle portion at its upperend, above the tubular element, by which the actuator can bereciprocated, and

(2) a driving connection with the plunger member at its lower end.

8. The fuel system of claim 7, wherein there is a fuel reservoir in theupper portion of the fuel tank with the bottom thereof spaced down fromthe level of the top wall of the tank, further characterized in that:

(A) the tubular pump member is integral with the bottom of saidreservoir and has its top contiguous to the bottom of the carburetor,and

(B) the carburetor mixing passage has a hole through its bottom wallthrough which the upper end of the bore in the tubular pump member iscommunicated with the mixing passage.

9. The internal combustion engine fuel system set forth in claim 7,further characterized by:

(A) means biasing the plunger member upwardly;

(B) valve means on the plunger member which opens during downwarddepression of the plunger member and closes upon upward movementthereof; and

(C) a check valve near the lower end of the bore in the tubular pumpmember arranged to open upon upward movement of the plunger member.

References Cited UNITED STATES PATENTS 2,101,536 12/1937 Ericson.2,999,562 9/ 1961 Lechtenberg. 3,118,433 1/1964 Lechtenberg 12341.313,188,060 6/ 1965 Kalert.

HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner.

1. IN COMBINATION: (A) A FUEL TANK FOR AN INTERNAL COMBUSTION ENGINE,SAID TANK HAVING A TOP WALL; (B) A CARBURETOR MOUNTED ON THE TOP WALL OFTHE FUEL TANK AND HAVING A MIXING PASSAGE WITH AN UPWARDLY FACING AIRINLET; (C) AN AIR FILTER SEATED ON THE INLET OF THE MIXING PASSAGE; (D)A TUBULAR SCREW PASSING DOWN THROUGH THE AIR FILTER AND THREADED INTOTHE BOTTOM WALL OF THE MIXING PASSAGE TO HOLD THE AIR FILTER INPOSITION; (E) A PRIMING PUMP CARRIED BY THE TOP WALL OF THE FUEL TANKAND LOCATED INSIDE THE TANK IN LINE WITH SAID TUBULAR SCREW, SAIDPRIMING PUMP HAVING AN INLET OPENING TO THE INTERIOR OF THE FUEL TANKAND AN OUTLET WHICH PASSES THROUGH THE BOTTOM WALL OF THE MIXINGPASSAGE; (F) A PLUNGER FOR THE PRINTING PUMP; AND